1. Field of the Invention
This invention relates to a operating pedal device for vehicle, and more particularly, to technologies of forming the operating pedal device for vehicle, having the load sensor for electrically detecting an operational force, in a compact structure at low cost.
2. Description of the Related Art
An operating pedal device for vehicle, such as a brake pedal device and an accelerator pedal device had been widely used. It includes (a) an operating pedal mounted on a pedal support fixedly secured to a vehicle to be pivotable about an axis of a support shaft and subjected to a depression operation by a driver; and (b) a reactive member connected to the operating pedal via at least one connecting section, which allows a relative pivotal movement between the operating pedal and the reactive member about a connecting pin, to which an output is transferred at a rate depending on an operational force of the operating pedal and which is applied with a reaction force corresponding to the output. One kind of such operating pedal device for vehicle has been known to have the load sensor that electrically detects the operational force.
With a device disclosed in, for instance, a Patent Publication 1, a push rod protruding from a master cylinder is connected to a connecting pin protruding from a side wall of an operating pedal to be relatively movable in an axial direction, so that a sensor can detect a displacement value of the push rod displaced relative to the connecting pin against the biasing force of a spring. Further, a Patent Publication 2 discloses technology in which a piezoelectric converter element is interposed as the load sensor between a clevis connected relatively pivotable to an operating pedal through a clevis pin, and an operating rod.    Patent Publication 1: U.S. Pat. No. 5,563,355    Patent Publication 2: Japanese Unexamined Patent Application Publication No. 11-230841
With the device disclosed in Patent Publication 1, however, since the push rod needs to have a slotted hole for connection with relative movement in an axial direction, a regularly used push rod cannot be used intact. Further, since the push rod is caused to pivot relative to the connecting pin with the depression operation of the operating pedal, the spring biasing the push rod, and the sensor detecting the displacement value, need to be pivotably mounted with respect to the connecting pin, resulting in a complicated structure. Moreover, since the push rod, the spring and the sensor are located in side areas of the operating pedal, a robust structure needs to be provided especially for the brake pedal or the like to ensure a stabilized operative condition. This causes a device to be structured on a major scale as a whole with an increase in cost.
With the device of Patent Publication 2, further, the piezoelectric converter element needs to be disposed between the clevis and the operating rod, and can hardly employs a regularly used operating rod and clevis, causing an increase in cost of the device.
The present invention has been completed on the background with the above issues in mind and has an object to provide an operating pedal device for vehicle having the load sensor for electrically detecting an operational force, which enables a rod and a clevis employed in the conventional pedal, to be used intact while enabling the provision of a compact structure at low cost.